Several methods to disinfect material are presently known in the art. Examples of such methods are methods based on chemical disinfection, radiation disinfection, thermal disinfection or thermal destruction. However, these methods show several drawbacks.
Chemical disinfection or sterilisation is a method that reaches its limits very rapidly, because the germs become more and more resistant and because it is often impossible to guarantee a good penetration of the disinfecting agent in the material to be disinfected (e.g. needles obstructed by blood, . . . ).
Disinfection or sterilisation by radiation is known to treat material such as medical waste.
However, this is an expensive technique requiring high investment costs.
Thermal disinfection or sterilisation is known as a very efficient technique to treat for example scalpels and other surgical instruments, but it does not allow to treat other materials such as medical waste with the same efficiency.
Thermal destruction is for example performed in an incinerator or furnace. This technique necessitates very large and expensive installations to respect the emission standards, and more particularly the dioxin emission standards. Moreover, this technique destroys and does not treat.
Today, the disinfection of metal surfaces as for example the surface of instruments is largely dominated by the treatment in humid heat (autoclaves) and many industrials have tried in vain to apply it to other fields, such as e.g. to medical waste.
For the disinfection of surgical instruments good results have been obtained. It has been shown that the reduction of the contamination can be reduced well over 6 Log by disinfecting surgical instruments in an autoclave.
For the disinfection of other materials such as cotton, a much lower disinfection level is actually obtained.
Indeed, in-depth disinfection of corpuses made of cellulose, glass or stainless steel fibers, such as medical waste, necessitates that all possible efforts have to be made to guarantee that the heat and the vapour reach all parts.
In most cases, this is realised by shredding and mixing together the waste in an autoclave.
However, the large variety of the materials that are susceptible to be contaminated and so the differences of specific thermal and heat conductivity lead to divergent thermal transfers. Metals will for example be heated more rapidly by the water vapour condensation than cellulose.
Therefore, it has been tried to apply an additional heating such as microwaves or high frequency heating, but the waste also presents a large diversity of dielectric properties leading to heterogeneous thermal transfers.
Indeed, several autoclave procedures have tried to prove their efficiency in experimental procedures to disinfect material infected by germs, but the fact that there exists a high heterogeneity in material does not guarantee a homogeneous treatment of the entire waste.